<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script src="jquery-3.3.1.min.js"></script>
  </head>
  <body>
    <div class="father">
      <div class="son">子元素</div>
    </div>
    <script>
      console.log($(".son").parent());
      console.log($(".father").find("div"));
    </script>
  </body>
</html>